Silicone-containing copolymer and bleed through resistant, ink receptive, and adhesive receptive coatings and coated substrates prepared therefrom

ABSTRACT

The present invention provides a novel copolymer and coating prepared therefrom. The coating which is capable of being written on effectively with both solvent-based and water-based inks is also bleedthrough resistant. A repositionable pressure sensitive adhesive note is capable of effectively adhering to the coating. The invention also provides substrates coated with the coatings and articles such as pads formed from the coated substrates.

FIELD OF THE INVENTION

The present invention provides a novel copolymer and coating preparedtherefrom, wherein a coating of the copolymer is capable of beingwritten on effectively with both solvent-based and water-based inks. Thecoating provides effective bleedthrough resistance when written on withboth solvent-based and water-based inks. The coating of the invention isof such a nature that a repositionable pressure sensitive adhesive notecan effectively adhere to it. The invention also provides substratescoated with novel coatings comprising the novel copolymers and novelarticles such as pads and rolls formed from the coated substrates.

BACKGROUND OF THE INVENTION

A variety of coatings for paper have been developed to impart manydifferent properties to the paper. These properties can include color,stiffness, receptivity to indicia, water resistance, bleedthroughresistance, release from pressure sensitive adhesives, etc.

Mertens, U.S. Pat. No. 5,154,962 describes a coating which comprisescopolymers of (A) free radically polymerizable vinyl monomer, (B) polarmonomer in a sufficient amount to impart a hydrated glass transititiontemperature (Tg) of -15 degrees C to 35 degrees C and a difference of atleast 20 degrees C between the hydrated and actual Tgs, and (C)siloxane-based polymer of a type and in an amount that will impart asatisfactory release value. The coating provides a substrate with anumber of properties including the ability to be effectively written onwith solvent and water-based inks, the indicia remaining firmly bondedand resistant to smearing. The coating also provides bleedthroughresistance to these inks. This coating, however, provides such goodrelease properties that repositionable pressure sensitive adhesives donot adhere to it. For example, Post-it™ Notes, and Post-It™ Tape Flags,available from Minnesota Mining and Manufacturing Company ("3M") of St.Paul, Minn., which have a repositionable pressure sensitive adhesivethereon, either immediately or after a very short period of time, falloff of a vertically positioned substrate having the Mertens' coatingthereon.

Thus there exists a need for a coating demonstrating ink receptivity andbleedthrough resistance, to which a repositionable pressure sensitiveadhesive note can effectively adhere.

SUMMARY OF THE INVENTION

We have discovered a novel copolymer which is capable of forming such acoating. The present invention provides a novel random copolymercomprising the reaction product of:

(a) a monomer selected from the group consisting of methyl acrylate,ethyl acrylate, and mixtures thereof;

(b) a monomer selected from the group consisting of N-vinyl pyrrolidone,N-vinyl caprolactam, and mixtures thereof;

(c) a monomer selected from the group consisting of acrylic acid,methacrylic acid, itaconic acid, maleic acid, fumaric acid,2-carboxymethyl acrylate, and mixtures thereof;

(d) a macromonomer having the general formula ##STR1## wherein X is avinyl group polymerizable with the monomers of elements (a), (b) and(c);

Y is a divalent linking group selected from the group consisting of--CH₂ --, --CH₂ CH₂ --, and --CH₂ CH₂ CH₂ --;

m is 20 to 2000;

each R is independently selected from the group consisting of hydrogen,C₁₋₈ alkyl, aryl, and alkoxy; and

wherein a coating of the copolymer is capable of being written oneffectively with both solvent-based and water-based inks;

wherein the coating is capable of providing effective bleedthroughresistance when written on with both solvent-based and water-based inks;

wherein a repositionable pressure sensitive adhesive note is capable ofeffectively adhering to the coating.

The present invention also provides an article comprising a substratecoated with a composition comprising the copolymer of the invention.Preferably, the substrate is paper.

One embodiment of the novel article comprises a substrate coated with acoating comprising the copolymer of the invention; wherein the coatingcomprising the copolymer is capable of being written on effectively withboth solvent-based inks and water-based inks;

wherein the coating is capable of providing effective bleedthroughresistance when written on with both solvent-based inks and water-basedinks; and

wherein a repositionable pressure sensitive adhesive note is capable ofeffectively adhering to the coating.

Another embodiment of the article of the invention is a pad comprising aplurality of the novel articles attached together.

Another embodiment of the article of the invention is a roll comprisingthe novel article rolled upon itself.

The article of the invention may optionally further comprise one or moreadditional coating(s) selected from the group consisting of pressuresensitive adhesives, release coatings, primers, etc., wherein theadditional coating(s) are coated on the substrate in area(s) other thanwhere the coating comprising the copolymer is coated. One particularlypreferred embodiment of the article of the invention is a padcomprising:

(a) a plurality of paper sheets, each sheet having a first side and asecond side;

(b) a layer of pressure sensitive adhesive adjacent at least a portionof an edge of the first side of each sheet;

(c) a release coating layer positioned on the second side of each sheetin a position which is opposite that of the pressure sensitive adhesivelayer which is on the first side of the sheet; and

(d) a coating layer comprising the copolymer of the present invention onat least a portion of the second side of each sheet other than where therelease coating layer is coated;

wherein the coating comprising the copolymer is capable of being writtenon effectively with both solvent-based inks and water-based inks;

wherein the coating is capable of providing effective bleedthroughresistance when written on with both solvent-based inks and water-basedinks;

wherein a repositionable pressure sensitive adhesive note is capable ofeffectively adhering to the coating; and

wherein the pad is assembled such that the sheets are stacked one uponanother, such that the release coating layer of each sheet is positionedagainst the pressure sensitive adhesive layer of a sheet which is aboveit so that an uppermost sheet is removable.

Preferably, the paper sheets of the pad are rectangular sheets of thesame dimension.

The pad may optionally further comprise a cardboard backing to which theplurality of sheets are attached.

Another preferred embodiment of an article of the invention is a rollcomprising:

(a) a sheet of paper having a first side and a second side;

(b) a layer of a pressure sensitive adhesive adjacent at least a portionof a longitudinal edge of the first side of the sheet;

(c) a layer of a release coating positioned on the second side of thesheet, positioned such that it is opposite the layer of pressuresensitive adhesive on the first side of the sheet;

(d) a coating comprising the copolymer of the present invention on atleast a portion of the second side of the sheet in area(s) where therelease coating is not present;

wherein the coating comprising the copolymer is capable of being writtenon effectively with both solvent-based inks and water-based inks;

wherein the coating is capable of providing effective bleedthroughresistance when written on with both solvent-based inks and water-basedinks;

wherein a repositionable pressure sensitive adhesive note is capable ofeffectively adhering to the coating;

wherein the sheet of paper is rolled upon itself in such a manner thatthe release layer is positioned directly against the pressure sensitiveadhesive layer.

Another preferred embodiment of the article of the invention is a rollcomprising:

(a) a sheet of paper having a first side and a second side;

(b) a first layer of a pressure sensitive adhesive adjacent at least aportion of a longitudinal edge of the first side of the sheet and asecond layer of pressure sensitive adhesive adjacent at least a portionof another longitudinal edge of the first side of the sheet opposite thefirst layer of pressure sensitive adhesive;

(c) two layers of a release coating on the second side of the sheet,positioned such that one is positioned opposite each layer of pressuresensitive adhesive on the first side of the sheet; and

(d) a coating comprising the copolymer of the present invention on atleast a portion of the second side of the sheet in area(s) where therelease coating layers are not present;

wherein the coating comprising the copolymer is capable of being writtenon effectively with both solvent-based inks and water-based inks;

wherein the coating comprising the copolymer is capable of providingeffective bleedthrough resistance when written on with bothsolvent-based inks and water-based inks;

wherein a repositionable pressure sensitive adhesive note is capable ofeffectively adhering to the coating comprising the copolymer;

wherein the sheet of paper is rolled upon itself in such a manner thateach release layer is positioned directly against the pressure sensitiveadhesive layer which is directly on the opposite side of the sheet.

Preferably for each above describe roll, the sheet of paper from whichthe roll is formed is rectangular.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a pad of the presentinvention.

FIG. 2 is a partial side view of the pad of FIG. 1.

FIG. 3 is a partial side view of an alternative embodiment of a pad ofthe present invention.

FIG. 4 is a cross-sectional side view taken along line 4--4 of FIG. 1showing the means by which the sheets are attached together, wherein anumber of centrally positioned sheets are not shown.

FIG. 5 is a side view of an alternative embodiment of a pad of thepresent invention.

FIG. 6 is a perspective front view of a dispensing assembly including aroll of the present invention shown mounted on a backboard supported bya presentation easel.

FIG. 6a is a cross-sectional side view of the sheet material of FIG. 6taken along line 6a--6a.

FIG. 6b is a cross-sectional side view of the sheet material of anotherembodiment of a roll of the invention.

FIG. 7 is an enlarged perspective front view of the dispensing assemblyof FIG. 6 removed from the backboard.

FIG. 8 is an exploded view of the dispensing assembly of FIG. 6.

FIG. 9 is a rear view of the dispensing assembly of FIG. 6.

FIG. 10 is an enlarged sectional view taken approximately along lines10--10 of FIG. 7.

FIG. 11 is an enlarged sectional view taken approximately along lines11--11 of FIG. 7 in which a rear portion of the dispensing assembly isnot sectioned.

DETAILED DESCRIPTION OF THE INVENTION

Copolymer of the Invention

Alkyl Acrylate Monomers

Useful alkyl acrylate monomers according to the present invention arethose selected from the group consisting of methyl acrylate, ethylacrylate, and mixtures thereof. These alkyl acrylate monomers areimportant in that they provide the copolymer with the followingproperties: bleedthrough resistance, film forming properties, andadhesive receptivity. If the monomers were not present in the copolymerthe polymer would be brittle and would peel off a substrate aftercoating thereon. Higher molecular weight acrylate monomers such aspropyl acrylate and butyl acrylate, for example, would not be useful inthe copolymer of the present invention since they would lower the glasstransition temperature of the polymer resulting in a tacky polymer whichwould not be useful for the intended coating applications.

Preferably the copolymer comprises about 30 to about 80 percent byweight, most preferably about 50 to about 55 percent by weight alkylacrylate monomers based upon the total weight of the alkyl acrylatemonomers, plus nitrogen-containing monomers, plus carboxylic acidfunctional monomers, plus silicone-containing macromonomers.

Nitrogen-Containing Monomers

The nitrogen-containing monomer selected from the group consisting ofN-vinyl pyrrolidone, N-vinyl caprolactam, and mixtures thereof, helpprovide the copolymer of the invention with advantageous properties suchas, for example, bleedthrough resistance and ink receptivity.

Preferably the copolymer comprises about 30 to about 50 percent byweight, most preferably about 40 to about 45 percent by weight nitrogencontaining monomers based upon the total weight of the alkyl acrylatemonomers, plus nitrogen-containing monomers, plus carboxylic acidfunctional monomers, plus silicone-containing monomers.

Carboxylic Acid Functional Monomers

It is required that the copolymer of the invention contain carboxylicacid functional monomer selected from the group consisting of acrylicacid, methacrylic acid, itaconic acid, maleic acid, fumaric acid,2-carboxymethyl acrylate, and mixtures thereof. These monomers helpprovide the copolymer of the invention with advantageous properties suchas, for example, ink receptivity, substrate adhesion, and coatingintegrity.

Preferably the copolymer comprises about 3 to about 10 percent byweight, most preferably about 4 to about 7 percent by weight carboxylicacid functional monomers based upon the total weight of the alkylacrylate monomers, plus nitrogen-containing monomers, plus carboxylicacid functional monomers, plus silicone-containing macromonomers.

Silicone-Containing Macromonomers

The previously mentioned silicone-containing macromonomers are alsoincluded in the copolymers of the invention. The term "monomer(s)" asused herein also includes "macromonomers". These monomers help provide acoating made from the copolymer with "good hand" (a smooth feel to thecoating). Preferably the formula of the silicone macromonomer isselected such that X is selected from the group consisting of: ##STR2##

Preferably the macromonomer is represented by ##STR3## wherein m is 100to 150.

Preferably the copolymer comprises about 0.5 to about 7 percent byweight, most preferably about 0.5 to about 2 percent by weightsilicone-containing macromonomer based on the total weight of the alkylacrylate monomers, plus nitrogen-containing monomers, plus carboxylicacid functional monomers, plus silicone-containing macromonomers.

Initiators

Free radical initiators are useful in forming the copolymers of theinvention. Useful thermal free radical initiators include but are notlimited to those selected from the group consisting of azo compoundssuch as 2,2'-azo-bis-(isobutyronitrile), dimethyl2,2'-azo-bis-isobutyrate, azo-bis-(dipheynyl methane),4-4'-azo-bis-(4-cyanopentanoic acid); peroxides such as benzoylperoxide, cumyl peroxide, tert-butyl peroxide, cyclohexanone peroxide,glutaric acid peroxide, lauroyl peroxide, methyl ethyl ketone peroxide;hydrogen peroxide, hydroperoxides such as tert butyl hydroperoxide andcumene hydroperoxide; peracids such as peracetic acid and perbenzoicacid; potassium persulfate; and peresters such as diisopropylpercarbonate. Preferred initiators include those selected from the groupconsisting of 2,2'-azo-bis-(isobutyronitrile),4-4'-azo-bis-(4-cyanopentanoic acid), and mixtures thereof.

Typically about 0.1 to about 0.6 percent by weight of initiator basedupon the total weight of the monomers is used in forming the copolymersof the invention, preferably about 0.3 to about 0.5 percent based uponthe total weight of the monomers.

Chain Transfer Agent

A chain transfer agent, it is believed, can optionally be used informing the copolymer of the invention. Examples of suitable chaintransfer agents it is believed include but are not limited to thoseselected from the group consisting of mercapto ethanol, octyl mercaptan,mercapto-propane diol, mercapto succinic acid, etc. Preferred chaintransfer agents, it is believed would include those selected from thegroup consisting of octyl mercaptan, mercaptopropane diol, and mixturesthereof.

Typically about 0.01 to about 0.2 percent by weight of a chain transferagent could be, it is believed, be included, preferably about 0.05 toabout 0.1 percent by weight, based upon the total weight of themonomers.

Properties of the Copolymer of the Invention

The molecular weight of the copolymer of the invention can vary.Typically, the number average molecular weight of the copolymer of theinvention ranges from about 15,000 to about 100,000, preferably about20,000 to about 80,000, and most preferably about 25,000 to about 50,000in order to optimize bleed through resistance and the smoothness of thecoating.

The inherent viscosity of the copolymer of the invention can vary.Typically the inherent viscosity ranges from about 0.28 dl/g to about0.48 dl/g measured in methanol in order to optimize bleed throughresistance and the smoothness of the coating.

The glass transition temperature of the non-silicone portion of thepolymer of the invention typically ranges from about 40 to about 90degrees C, preferably about 50 to about 80 degrees C.

The amount of monomers and other components making up the copolymer canvary as long as the requisite claimed properties are present in acoating prepared therefrom. These include ink receptivity, bleedthroughresistance, and adherence of repositionable pressure sensitive adhesivenotes.

The typical percentages are mentioned previously. If the amount of thealkyl acrylate is less than about 30 weight percent the coating tends tobe uneven. If the amount of the alkyl acrylate is greater than about 60weight percent the coating tends to be tacky resulting in poor inkadherence. If less than about 30 weight percent NVP is present thecoating tends to streak and demonstrate poor adherence to inks. Ifgreater than about 50 percent by weight NVP is present the coatingprepared therefrom would be too hydrophilic to demonstrate bleedthroughresistance. If less than about 3 weight percent of the carboxylic acidfunctional monomer is present the coating tends to be tacky. If greaterthan about 10 weight percent of the carboxylic acid functional monomeris present the coating tends to be brittle and flaky. If the siloxanemacromonomer is present in an amount greater than about 7 weight percentthe coating would tend to demonstrate release properties, thusinterfering with the ability of pressure sensitive adhesiverepositionable notes to adhere thereto.

Method of Making the Copolymer of the Invention

The copolymer of the invention can be prepared by a number of differentmethods. Examples of such methods include but are not limited to thoseselected from the group consisting of free radical polymerization insolvent, emulsion polymerization, suspension polymerization, etc.

The following is an example of a typical free radical polymerizationprocess in solvent. Into a closed reactor is charged the monomers, theinitiator, optional chain transfer agent, if included, and an organicsolvent such as methyl ethyl ketone, isopropyl alcohol, etc. Thecomponents can be charged in any order. The resulting mixture is purgedto remove at least most of the oxygen. The mixture is heated to atemperature of typically about 50 to about 80 degrees C, preferablyabout 55 to about 65 degrees C, typically with agitation, for a periodof time of about 12 to 24 hours to allow reaction to occur, preferablyabout 16 to about 24 hours until the total amount of any unreactedmonomers is less than about 0.8 percent by weight based upon the totalweight of the monomers plus solvent, most preferably about 0.3 to about0.6 percent by weight based upon the total weight of the monomers plussolvent. This mixture is typically of very high Brookfield viscosity(typically above about 30,000 cps). To this mixture is added additionalorganic solvent in one or more charges with agitation as necessary inorder to form a mixture having a percent solids content of about 12 toabout 21, preferably about 18 to about 20 percent. The inherentviscosity of such a solution is typically about 0.28 to about 0.48 dl/gmeasured in methanol.

Coatings of the Copolymer of the Invention

Coatings comprising the copolymer of the invention can be coated onvarious substrates. These coatings are typically continuous. Examples ofsuitable substrates include, for example, films and nonwovens. Examplesof suitable films include but are not limited to those selected from thegroup consisting of polyester, polypropylene, polyethylene, etc.Examples of suitable nonwovens include but are not limited to thoseselected from the group consisting of cellulosics such as paper,polypropylene, polyester, etc. Paper is a preferred substrate. Typicallythe coating comprising the copolymer is provided on a substrate bycoating one of the aforementioned solutions on the substrate andallowing the solvent to dry off. Typically solutions are coated thathave a percent solids content of about 10 to about 20, preferably about12 to about 15. The dry coating weight on a substrate typically variesfrom about 3 to about 16 g/m², preferably about 5 to about 12 g/m².

In addition to comprising the copolymer of the invention it is theorizedthat the coatings of the invention can further comprise one or more ofthe following: dyes, defoaming agents, etc.

Articles of the Invention

As mentioned previously the present invention also provides an articlecomprising a substrate coated with a coating comprising the copolymer ofthe invention. Rolls and pads may be provided from the articles.

One preferred embodiment of the article of the invention comprises asheet (such as a paper sheet, for example, having two sides). One sideof the sheet has a layer of pressure sensitive adhesive on a portionthereof. The other side of the sheet has a layer of release coating on aportion thereof and a layer of a coating comprising the copolymer of theinvention on another portion of the same side of the sheet as therelease coating but on a portion of the sheet where the release coatingis not present. The layer of pressure sensitive adhesive is typicallycontinuous although it may be discontinuous. Examples of discontinuouscoatings include dots, stripes, etc.

The layer of the release coating is coated on the side of the sheetdirectly opposite the pressure sensitive adhesive. The area of therelease coating would typically be as large or larger than the area ofthe pressure sensitive adhesive on the opposite side of the sheet. Therelease coating layer would typically be continuous although it may bediscontinuous as long as it provides acceptable release. One skilled inthe art would be able to select a suitable release coating of suitabledimension and position such that it would provide appropriate releasewhen positioned against the pressure sensitive adhesive on the same oranother sheet.

On the same side of the sheet as the release coating, but in area(s)where the release coating is not present is a layer of a coatingcomprising the copolymer of the invention. The side of the sheet havingthe release coating and the coating of the copolymer of the inventiontypically does not have any uncoated areas. Typically, the releasecoating is positioned adjacent to one or two edges of the sheet and therest of that side of the sheet is coated with the copolymer of theinvention to maximize the area which can be written on and to whichother repositionable pressure sensitive adhesive articles (such asnotes, flags, etc.) can adhere. A release coating layer when positionedadjacent an edge may be positioned a distance from the edge (typically asmall distance) Or directly up against the edge.

As indicated previously one of the specific preferred embodiments of thearticle of the invention is a pad comprising a stack of paper sheets.Each sheet has two sides. One side of each sheet typically is uncoatedexcept for a layer of a repositionable pressure sensitive adhesiveadjacent one edge.

A preferred embodiment of the present invention provides a pad of thetype including a multiplicity of aligned flexible sheets attachedtogether along one edge portion to form a stack from which any ofseveral uppermost individual sheets can either be pivoted away from anadjacent sheet, or can be separated from the stack and releasablyadhered to a support surface by repositionable pressure sensitiveadhesive on the sheet that can adhere well to many rough surfaces; whichpads are particularly useful when made large in size and to include astiff back card whereby they can be supported at the front of a roomduring a meeting in a generally vertical position and used to recordlists of items or ideas generated during the meeting.

According to a preferred embodiment of the present invention there isprovided a pad comprising a multiplicity of flexible sheets each havinga band of repositionable pressure sensitive adhesive coated on itssecond (rear) surface adjacent to and spaced by a small predeterminedspacing from a first edge and spaced by a large predetermined spacingfrom a second opposite edge. The sheets are disposed in a stack with thecorresponding edges of the sheets aligned, the first (front) and second(rear) surfaces of adjacent sheets facing each other, and the band ofrepositionable pressure sensitive adhesive on each sheet adhering it tothe adjacent sheet in the stack. On the front surfaces of the sheets, inseparate areas are layers of the coating of the invention and also alayer of a release coating. The release coating at least covers the areawhich the pressure sensitive adhesive on the rear surface would contactwhen the sheets are in a stacked position.

Preferably, when used as a flip chart, the pad further includes a stiffback card to which the bottom most sheet in the stack is attached, whichback card is at least coextensive with the sheets in the stack. Thatback card can have a top edge aligned with the first edges of thesheets, or, as illustrated herein, can have a top portion projectingpast the aligned first edges of the sheets, which top portion has aperipheral support edge generally parallel to the first edges of thesheets over which support surface one or more of the sheets in the padcan be supported after they are peeled away from the adjacent underlyingsheet. The top portion of the back card can have an elongate openinggenerally aligned with and spaced from that support edge with the partof the top portion between the opening and that support edge providing ahandle by which the pad can easily be moved from place to place. Toprovide space for that opening the top portion of the back card shouldproject in the range of about 5 to 10 centimeters (2 to 4 inches) pastthe first edges of the sheets. Also, the top portion of the back cardcan have two aligned parallel elongate through slots positioned adjacentopposite sides of the back card and adapted to receive the support pegson some types of easels on which the pad might be supported.

Referring now to FIG. 1, there is shown a preferred embodiment of a padof the present invention generally designated by the reference numeral110, which pad 110 is in an embodiment sometimes called a "flip chart"or an "easel pad" which can be supported on a support such as an easel(not shown) at the front of the room during a meeting and used to recordlists of items or ideas generated during the meeting.

Generally the pad 110 comprises a multiplicity of flexible sheets 112(e.g., 30 sheets 112), each sheet 112 being generally of the same size,having first (front) and second (rear) surfaces having, upon removalfrom the pad 110, peripheral edges including first and second oppositeedges 115 and 116, having a band 118 (see FIG. 2) of repositionablepressure sensitive adhesive coated on the second (rear) surface adjacentto and spaced by a small predetermined spacing 109 from the first edge115 and spaced by a large predetermined spacing from the second edge116, the sheets 112 being disposed in a stack 117 with the correspondingperipheral edges of the sheets 112 aligned, the first (front) and second(rear) surfaces of adjacent sheets 112 facing each other, and the band118 of repositionable pressure sensitive adhesive on each sheet 112adhering that sheet 112 to the adjacent sheet 112 in the stack 117. Thefirst edge 115 is defined by the perforations 111 extending through eachsheet 112. A band of release coating 107 is coated on the first (front)of each sheet 112 in the same position but on the opposite side of thesheet 112 as the band of repositionable pressure sensitive adhesive 118.

The coating of the invention 105 which is bleed through resistant, inkreceptive, and pressure sensitive adhesive receptive is coated on thefirst (front) surface of each sheet 112 in the area between the releasecoating 107 and the edge 116 of each sheet 112. These terms are definedbelow. Writing 103 from solvent and/or water based markers is evident onthe portion of the sheet 112 coated with the coating 105 of the presentinvention. (See FIG. 1) Repositionable pressure sensitive adhesive notes104 are adhered to the front surface of a sheet 112 over an area coatedwith the coating 105 of the invention.

The sheets 112 can be, for example, of paper that weighs 15.4 pounds(7.0 kg) per ream 17 inch (432 mm) by 22 inch (559 mm) by 500 sheet insize, such as the paper commercially designated "Form Run Bond" that isavailable from Georgia Pacific, Kalamazoo, Mich., and may, for example,have a dimension between the first and second edges 115 and 116 of about775 millimeters (30.5 inches) and a width in a direction parallel to thefirst and second edge 115 and 116 of about 635 millimeters (25 inches).

Referring to FIG. 1, the pad 110 further includes a back card 122 of astiff material (e.g., rigid cardboard or chipboard 864 millimeters (34inches) high by 635 millimeters (25 inches wide) having a from surfaceto which the second (rear) surface of the bottom most sheet 112 in thestack 117 is attached. The front surface of the back card 122 iscoextensive with the sheets 112 in the stack 117, and the back card 122has a top portion 124 projecting past the aligned top edges 127 of thesheets 112. The aligned top edges 127 are parallel to the first edges115 and the second edges 116. The top portion 124 has a peripheralsupport edge 126 generally parallel to the first edges 115 of the sheets112 preferably spaced about 9 centimeters (3.5 inches) from the firstedges 115 of the sheets 112, over which support edge 126 one or more ofthe sheets 112 in the stack 117 can be supported after the bands 118 ofpressure sensitive adhesive on those sheets 112 have been peeled awayfrom the adjacent underlying sheet 112 and those sheets 112 are bentback over the support edge 126. The top portion 124 has an elongatethrough opening 130 generally aligned with and spaced from the supportedge 126 with the part of the top portion 124 between the opening 130and the support edge 126 providing a handle for the pad 110 by which thepad 110 can conveniently be manually moved around. Also, the top portion124 has two aligned parallel elongate through slots 131 positionedadjacent opposite sides of the back card 122 and aligned parallel to thesupport edge 126, the slots 131 being adapted to receive the supportpegs on some types of easels on which the pad 110 might be supported.

The back card 122 also has a bottom portion 134 projecting past thealigned second edges 116 of the sheets 112. The bottom portion 134 has aperipheral supported edge 136 generally parallel to the second edges 116of the sheets 112 and spaced in the range of about 0.6 to 2.5centimeters (0.25 to 1 inch) and preferably about 1.3 centimeters (0.5inch) from the second edges 116 of the sheets 112, which supported edge136 is adapted to be supported on a support surface such as on thesupport ledge of an easel while the bottom portion 134 spaces the secondedges 116 of the sheets 112 sufficiently from that support surface toafford easy manual access to the sheets 112 as may be needed to use thepad 110. Staples 113 extend through the top portion 124 of the back card122, the sheets 112 and the back of the back card 122.

Referring to FIG. 2, preferably the band 118 of repositionable pressuresensitive adhesive that extends parallel to the first edge 115 iscontinuous, and has a width in a direction normal to the first edge 115in the range of 3.75 to 6.25 centimeters (1.5 to 2.5 inches), with thatband 118 preferably being about 5 centimeter (2 inches) wide.Alternatively, however, the band 118 of repositionable pressuresensitive adhesive could comprise a plurality of spaced areas coatedwith pressure sensitive adhesive that also has a width in a directionnormal to the first edge 115 in that range.

The portion of the first (front) surface of each sheet 112 to which theband of adhesive 118 on the adjacent sheet is adhered to help retain thesheets 112 in the stack 117 is coated with a layer 107 of a suitablerelease material (see FIG. 2) to provide a desired releasable level ofadhesion between the band of adhesive 118 and the adjacent sheet 112.

After writing 103 and/or positioning repositionable adhesive notes 104on the front surface of the top sheet 112 in the pad, if he/she choosesto do so, a user of the pad 110 can peel the band of adhesive 118 onthat top sheet 112 away from the second sheet 112 in the pad 110 bypulling on the top sheet 112 adjacent its second edge 116 in a directiongenerally at a right angle to the front surface of the underlying sheet112. (See FIGS. 1 and 2) Tension in the top sheet 112 caused by suchpulling will progressively peel the band 118 of adhesive from theunderlying sheet 112, and the user will feel the top sheet 112 move muchmore easily away from the underlying sheet 112 as the last portion ofthe band 118 separates from the underlying sheet 112, thereby providingthe user with a tactile signal that he should stop pulling on the sheet112 if he does not wish to separate the top sheet 112 from the pad 110via the perforations 111. If the user does not wish to remove the topsheet 112 from the pad 110, he can then stop pulling on the sheet andbend the top sheet 112 back over the support edge 126 on the top portion124 of the back card 122, exposing the front surface of the underlyingsheet. If the user wishes to remove the top sheet 112 from the pad 110he/she can simply tear its first edge 115 away from the pad 110 via theperforations 111, whereupon the user may releasably adhere the removedsheet to a vertical support surface using the band 118 of pressuresensitive adhesive. After the uppermost sheet 112 is either bent backover the support edge 126 or removed, a user may similarly peel awayeach successive underlying sheet 112 and either also bend it back overthe support edge 126 or remove it from the pad 110. Subsequently, ifdesired, the user can reposition any sheets 112 bent back over thesupport edge 126 in their original position on the pad and readhere themto the underlying sheet I 12 on the pad 110 using the bands 118 ofadhesive. The bands 118 of adhesive will provide good adhesion to evenrough vertical support surfaces, such as those of cloth or paintedcement blocks, while affording clean removal of the sheets from allsurfaces without leaving adhesive residue or damaging the surface suchas by removing paint, paper, or fabric from the surfaces.

FIG. 4 is a cross-sectional side view of the pad of FIG. 1 wherein anumber of the centrally positioned sheets are not shown.

Referring now to FIG. 3, there is shown a partial side view of analternate embodiment of a pad of the present invention, which pad isalso in an embodiment sometimes called a "flip chart" or an "easel pad"which can be supported on a support such as an easel (not shown) at thefront of the room during a meeting and used to record lists of items orideas generated during the meeting.

Generally the pad comprises a multiplicity of flexible sheets 112';(e.g., 30 sheets 112'), each sheet 112' being generally of the samesize, having first (front) and second (rear) surfaces having, uponremoval from the pad, peripheral edges including first and secondopposite edges 115' and 116', having a band 118' of repositionablepressure sensitive adhesive coated on the second (rear) surface adjacentto and spaced adjacent and directly up against first edge 115' andspaced by a large predetermined spacing from the second edge 116', thesheets 112' being disposed in a stack 117' with the correspondingperipheral edges of the sheets 112' aligned, the first (front) andsecond (rear) surfaces of adjacent sheets 112' facing each other, andthe band 118' of repositionable pressure sensitive adhesive on eachsheet 112' adhering that sheet 112' to the adjacent sheet 112' in thestack 117'. The first edge 115' is defined by the perforations 111'extending through each sheet 112'. A band of release coating 107' iscoated on the first (front) of each sheet 112' in the same position buton the opposite side of the sheet 112' as the band of repositionablepressure sensitive adhesive 118'. The aligned top edges of the sheets112' are identified as 127'.

The coating of the invention 105' which is bleed through resistant, inkreceptive, and pressure sensitive adhesive receptive is coated on thefirst (front) surface of each sheet 112' in the area between the releasecoating 107' and the edge 116' of each sheet 112'. Writing from solventand/or water based markers would be evident on the portion of the sheet112' coated with the coating 105' of the present invention.Repositionable pressure sensitive adhesive notes would adhere to thefront surface of a sheet 112' over an area coated with the coating 105'of the invention.

Referring now to FIG. 5, there is shown a partial view of an alternateembodiment of a pad of the present invention.

Generally the pad comprises a multiplicity of flexible sheets 212;(e.g., 30 sheets 212), each sheet 212 being generally of the same size,having first (front) and second (rear) surfaces having, upon removalfrom the pad, peripheral edges including first and second opposite edges215 and 216, having a band 218 of repositionable pressure sensitiveadhesive coated on the second (rear) surface adjacent to and spacedadjacent and directly up against first edge 215 and spaced by a largepredetermined spacing from the second edge 216, the sheets 212 beingdisposed in a stack 217 with the corresponding peripheral edges of thesheets 212 aligned, the first (front) and second (rear) surfaces ofadjacent sheets 212 facing each other, and the band 218 ofrepositionable pressure sensitive adhesive on each sheet 212 adheringthat sheet 212 to the adjacent sheet 212 in the stack 217. A band ofrelease coating 207 is coated on the first (front) of each sheet 212 inthe same position but on the opposite side of the sheet 212 as the bandof repositionable pressure sensitive adhesive 218.

The coating of the invention 205 which is bleed through resistant, inkreceptive, and pressure sensitive adhesive receptive is coated on thefirst (front) surface of each sheet 212 in the area between the releasecoating 207 and the edge 216 of each sheet 212. Writing from solventand/or water based markers would be evident on a sheet 212 coated withthe coating 205 of the present invention. Repositionable pressuresensitive adhesive notes would adhere to the front surface of a sheet212 over an area coated with the coating 205 of the invention. A layerof padding compound 201 adheres the sheets 212 together via their edges201. As each individual sheet 212 is removed some of the paddingcompound 201 is also removed.

A small amount of padding compound 201 is removed from the pad 110 uponremoval of each sheet 212. The layer 201 of padding compound can beformed with any of several commercially available adhesive paddingcompound materials, such as "Merit" padding adhesive from Merrit PadCo., Plainsville, Ohio; "Hurst Graphics" padding compound from HurstGraphics, Los Angeles, Calif.; or "Champadco" padding cement fromChampion Mfg. Co., Charlotte, N.C.

The pad of the present invention has now been described with referenceto only several of many embodiments thereof. It will be apparent tothose skilled in the art that many changes can be made in theembodiments described without departing from the scope of the presentinvention.

Rolls

As indicated previously the present invention also provides rolls coatedwith the coating of the invention. Various roll constructions can becoated with the coating of the invention. Various dispensing assembliescan be used with the rolls.

The present invention provides in another embodiment a roll of sheetmaterial having the coating of the invention disposed thereon in arelatively compact easily portable dispensing assembly for dispensinglengths of sheet material (e.g., paper). The dispensing assembly thatcan be adapted to be mounted on an end portion of a backboard that maybe supported on or included in a presentation easel or other supportstructure.

An embodiment of a dispensing assembly useful according to the presentinvention includes a cylindrical core having an axis; a length of sheetmaterial helically wound into a roll coaxially around that core, theroll having axially spaced end surfaces and the core having oppositeprojecting end portions projecting axially past those end surfaces; andan enclosure. The enclosure includes a front portion comprising wallsdefining an elongate channel-like part of the front portion that isgenerally U-shaped in cross section, has opposite ends and has first andsecond elongate opposite edges extending between its ends, and end wallsacross the ends of the channel-like part with those end walls and thechannel like part defining a chamber having an open side between thefirst and second elongate opposite edges of said channel-like part; anda rear portion including a rear wall having opposite ends, oppositefirst and second edges extending between its ends, and an attachmentpart adjacent its second edge including means adapted to be releasablymounted on support members on one end portion of a backboard. The frontand rear portions include journal surface portions at each of their endsthat are opposed in the closed position of the front and rear portionsto define sockets at those ends that receive and journal the projectingend portions of the core with the roll in the chamber. The journalsurface portions are separated when the front and rear portions areseparated to afford removal of the projecting end portions of the corefrom between the journal surface portions. The first edges of the wallsare spaced to define an elongate opening parallel to the axis throughwhich lengths of sheet material from the roll can be pulled from saidroll; and cutting means are provided on the first edge of the frontportion along the opening for affording cutting a dispensed length ofsheet material projecting through the opening from sheet material on theroll by pulling the dispensed length of sheet material into engagementwith those cutting means.

Preferably, the front portion of the housing is vacuum formed oftransparent polymeric material to afford visually inspecting the amountof sheet material remaining on the roll.

Also, preferably the rear portion is formed of polymeric material, thefront portion includes a flange wall around the open side of the channelpositioned face to face with said rear wall when the front and rearportions are in their closed position, and the means for removablymounting and releasably retaining the front portion on the rear portionin the closed position and for affording manual removal of the frontportion from the rear portion comprises a plurality of projections fromsaid flange frictionally received in sockets in the rear wall.

Referring now to FIGS. 6, 6a, and 7-11 there is illustrated anembodiment of a dispensing assembly that is generally designated by thereference numeral 10. The dispensing assembly 10 is adapted to bemounted on a backboard such as the backboard 12 illustrated in FIG. 6that has opposite end portions and as illustrated is supported on apresentation easel 13, but which could as well be supported on anothersupport structure such as a conference room presentation cabinet.

The dispensing assembly 10 includes a cylindrically tubular core 11having an axis, and a length of sheet material 14 (e.g., paper) havingfront and rear surfaces 15 and 16 respectively, which length of sheetmaterial 14 is helically wound into a roll 18 positioned coaxiallyaround the core 11 with its front surface 15 outermost in the roll 18.The core 11 has projecting end portions 17 projecting axially pastopposite end surfaces 19 of the roll 18. Two spaced strips 20 ofrepositionable pressure sensitive adhesive extend longitudinally alongthe rear surface of the length of sheet material 14, with each strip 20being closely spaced from a different one of the longitudinal edges ofthe sheet material 14. Both the release layer strips 21 and the pressuresensitive adhesive strips 20 are positioned adjacent edges of the sheetmaterial 14. However, the release layer strips 21 are positioneddirectly up against the edges whereas the pressure sensitive adhesivestrips 20 are spaced a small distance from the edges. Two strips ofrelease coating 21 are coated on the front surface of the sheet material14 but directly opposite the strips of pressure sensitive adhesive 20coated on the back of the street material 14. The coating 29 of thepresent invention is coated on the front surface of the sheet material14 in the area not coated with release coating strips 21. Writing 3 fromsolvent and/or water based markers is evident on the sheet material 14in FIG. 6. Repositionable pressure sensitive adhesive notes 5 adhere tothe surface of the sheet material 14 coated with the coating 29 of theinvention as seen in FIG. 6. The sheet material 14 can be of anysuitable width with sheet material 14 at least 45 centimeters or 18inches wide being useful for many purposes, and paper about 61centimeters or 24 inches in width being most useful when intended foruse on the backboard of conventional presentation easels.

FIG. 6a is a cross-sectional side view of the sheet material 14 of FIG.6 taken along line 6a--6a. The sheet material is identified as 14, therelease coating is identified as 21, and the coating of the invention isidentified as 29. In FIG. 6a the release layer strips 21 are wider thanthe pressure sensitive adhesive slips 20. When the sheet material 14 isin its rolled up position the strips are positioned such that pressuresensitive adhesive strips 20 are in contact with a release coatedsurface 21.

FIG. 6b is a cross-sectional side view of the sheet material 14' of analternate embodiment of a roll of the invention. The sheet material isidentified as 14', the release coating strips are identified as 21', andthe coating of the invention is identified as 29'. In FIG. 6b therelease layer strips 21' are as wide as the pressure sensitive adhesivestrips 20' and the release strips 21' and pressure sensitive adhesivestrips 20' extend all the way to the edge of the sheet material 14'.When the sheet material is in its rolled up position the strips arepositioned such that pressure sensitive adhesive strips 20' are incontact with a release coated surface 21'.

Referring to FIGS. 6 and 7-9 the dispensing assembly 10 also includes anenclosure 22 having walls defining a chamber 24, and journaling means,later to be explained, mounting the core 11 supporting the roll 18 ofsheet material 14 within the chamber 24 for rotation about its axis.Those walls define an elongate opening 26 parallel to the axis of theroll 18 and core 11 through which lengths of the sheet material 14 canbe pulled from the roll 18. Cutting means 28 is provided on one of thewalls along the opening 26 which affords cutting a dispensed length ofthe sheet material 14 projecting through the opening 26 from the sheetmaterial 14 on the roll 18 by pulling the end of the dispensed length ofsheet material 14 along the cutting means 28 sequentially intoengagement with the cutting means 28. Also included in the dispensingassembly 10 are means on the enclosure 22 adapted to be releasablyattached or mounted on one end portion of the backboard 12 (i.e.,typically on the upper end portion as illustrated in FIG. 6) with theopening 26 adjacent the other end portion of the backboard 12.

The enclosure 22 includes front and rear portions 34 and 35 defining thechamber 24 in which the core 11 supporting the roll 18 of sheet material14 is journalled. Those front and rear portions 34 and 35 are manuallyseparable so that when the roll 18 of sheet material has all beendispensed, the portions 34 and 35 of enclosure 22 can be separated, thecore 11 can be removed, and a new roll 18 of sheet material on a core 11can be positioned in the chamber 24 of the again assembled enclosure 22.The front portion 34 of the enclosure 22 is vacuum formed of polymericmaterial (e.g., 0.060 inch thick sheet styrene) which preferably istransparent to afford visually inspecting the amount of sheet material14 remaining on the roll 18. The front portion 34 comprises wallsdefining an elongate channel-like part 38 of the front portion 34 thatis generally U-shaped in cross section, and end wails 40 across the endsof the channel-like part 38. The end walls 40 and the channel-like part38 define a major part of the chamber 24 that has an open side, and thefront portion 34 includes a co-planar flange 42 projecting outwardlyfrom around the open side of the chamber 24. The flange 42 has anelongate edge which is defined by surfaces disposed at about a rightangle with respect to each other to provide the cutting means 28 for thesheet material 14.

The rear portion 35 of the enclosure 22 is also vacuum formed ofpolymeric material (e.g., of 0.060 inch (1.52 mm) thick sheet styrene).The rear portion 35 comprises a rectangular rear wall 48 having oppositeends, a first edge 50 extending between its opposite ends and definingone side of the opening 26 through which the sheet material 14 isdispensed, a rectangular recess 51 adjacent the front edge defining aminor portion of the chamber 24 in which a portion of the roll 18 isreceived, an opposite second edge 52, and an attachment portion 54adjacent the second edge 52 including the means on the enclosure 22adapted to be releasably attached on one end portion of the backboard12.

Means for removably mounting and releasably retaining the front portion34 on the rear portion 35 in a closed position while affording manualremoval of the from portion 34 from the rear portion 35 at the sides andbottom are provided. A plurality of sockets 56 are present in tab-likeportions 57 of the flange 42, which sockets 56 are adapted to receivemating projections 59 in the rear wall 48. Typically the interconnectbetween projections 59 and sockets 56 is so strong that using normalamount of force the assembly stays sealed at the top, only opening atthe sides and bottom. Also, the rear wall 48 has an upwardly projectingrim 60 around three sides of the recess 52 (i.e., all sides but the sideadjacent the opening 26). That rim 60 is adapted to fit closely within amating recess around the front portion 34 where the flange 42 joins thechannel like part 38 and the end walls 40 to help align the front andrear portions 34 and 35 when they are in their closed position.Referring to FIG. 11 projections 41 extending from front portion 34 canbe frictionally and removably received in mating sockets 39 in rearportion 35.

The journalling means for the projecting end portions 17 of the core 11are provided by opposed journal surface portions 62 and 63 (see FIG. 11)at each of the ends of the front and rear portions 34 and 35. Thosejournal surface portions 62 and 63 at each of the ends are opposed inthe closed position of the front and rear portions 34 and 35 shown inFIGS. 6, 7, 10, and 11 to receive and journal the projecting endportions 17 of the core 11 when the core 11 is in the chamber 24; andthose journal surface portions 62 and 63 are separated (See FIG. 8) whenthe front and rear portions 34 and 35 are separated to afford removal ofthe end portions 17 of the core 11 from between them.

The journal surface portions 63 on the rear portion 35 are partiallydefined by spaced projections 65 along the rim 60, whereas the journalsurface portions 62 on the front portion 34 are defined by parts ofarcuate inner surfaces on projecting parts 67 of the end walls 40 thatalso receive the spaced projections 65 when the from and rear portions34 and 35 are in their closed position.

The first edge 50 of the rear portion 35 is partially defined by spacedrecesses between projecting portions 70 of the rear wall 35, with thoserecesses providing finger access to the newly severed end of sheetmaterial 14 in the opening 26 after a length of sheet material 14 hasbeen dispensed from the dispensing assembly 10.

The attachment portion 54 of the rear wall 48 has two aligned elongatethrough slots 71 positioned adjacent opposite ends of the attachmentportion 54 parallel to its second edge 52, which slots 71 are adapted toreceive the support pegs or screws 72 on many conventional types ofbackboards such as the backboard 12 illustrated in FIG. 6 that cansupport the dispensing assembly 10. As is illustrated in FIG. 6 and istypical of a number of backboards, the support screws 72 threadablyreceive wing nuts 73 that can bear against a bar 74 that is placed overthe attachment portion 54 and also receives the screws 72 in spacedopenings so that the screws 72, bar 74 and wing nuts 73 clamp theattachment portion 54 to the end portion of the backboard 12.

Also, the attachment portion 54 of the rear wall 48 has a longitudinallycentered elongate opening 76 generally parallel with and spaced from itssecond edge 52 with the part of the attachment portion 54 between theopening 76 and the second edge 52 providing a handle by which thedispensing assembly 10 can easily be moved from place to place.

It will be apparent to those skilled in the art that many changes can bemade in the embodiments described without departing from the scope ofthe present invention. For example, the enclosure could be made withwalls of polymeric material. The sheet material could comprise apolymeric film. The dispensing assembly would be useful for dispensinglengths of sheet material of the types described for use on surfacesother than the surfaces of backboards, such as on office or cubiclewalls, and for that purpose, the slots 71 in the attachment portion 54would not be needed. Also, the rear portion of the enclosure could beincorporated in or permanently attached to an end portion of abackboard.

Examples of suitable release coatings for any of the articles of theinvention include but are not limited to those selected from the groupconsisting of release polymers which contain hydrophobic groups, such aslong chain alkyl groups, organopolysiloxane groups, fluoroalkyl groups,fluoroalkylene groups such as poly(perfluoroalkyleneoxy) or combinationsthereof which can be prepared by polymerizing a mixture comprisingmonomers which contain such groups. Such polymers and monomers includemany that are well known. See, for example, the description ofpolysiloxane-containing monomers in U.S. Pat. Nos. 5,154,962 and5,032,460; the description of long chain alkyl-containing monomers inU.S. Pat. No. 3,022,988; and the description of fluoroalkyl-containingmonomers in U.S. Pat. Nos. 3,318,852; 4,830,910; 4,873,140; 3,944,527;and 3,574,791 (all of which are incorporated by reference herein).Another useful release material is described in U.S. Pat. No. 2,532,011,incorporated by reference herein.

One skilled in the art would be able to select a suitable pressuresensitive adhesive for use in the present invention. Preferably thepressure sensitive adhesive is a repositionable pressure sensitiveadhesive. The pressure sensitive adhesive used should have sufficientstrength to hang a coated substrate of the invention on a verticalsurface. Examples of suitable pressure sensitive adhesives include butare not limited to those selected from the group consisting ofacrylates, rubber resins, microsphere adhesives such as those describedin WO 94/19420 (Sep. 1, 1994) and U.S. Pat. Nos. 3,691,140 and 5,045,569(all incorporated by reference herein), patterned adhesives, hot meltadhesives, etc.

Various pressure sensitive adhesives can be used according to thepresent invention. The peel adhesion of the pressure sensitive adhesivecan vary depending upon the intended application of the article of theinvention. The peel adhesion of the pressure sensitive adhesive shouldbe such that the surface to which it is to be adhered, such as a paintedwall for example, will not be damaged by the adhesive upon removal. Theadhesive should be suitable for adhering a substrate to a verticalsurface, but removable without damage to the surface.

    ______________________________________                                        ABBREVIATIONS                                                                 The following abbreviations are used herein:                                  ______________________________________                                        MA       methyl acrylate                                                      AA       acrylic acid                                                         NVP      n-vinyl pyrrolidone                                                  MEK      methyl ethyl ketone                                                  SiMac    methacrylate functional polydimethyl siloxane                        I.V.     inherent viscosity                                                   NVC      N-vinylcaprolactam                                                   EA       ethyl acrylate                                                       MAA      methacrylic acid                                                     Vazo 64  2,2'-azo-bis-(isobutyronitrile) available from DuPont                IPA      isopropyl alcohol                                                    Rxn.     reaction                                                             Tmp.     temperature                                                          Comp.    Comparative                                                          wt. %    weight percent                                                       na       not available                                                        Ex.      example                                                              PSA      pressure sensitive adhesive                                          ______________________________________                                    

EXAMPLES

The following examples further illustrate but do not limit the presentinvention. All parts, percentages, ratios, etc. in the Examples andelsewhere herein are by weight unless indicated otherwise.

Copolymer Synthesis

Example 1

In a 1 liter amber glass jar were charged 112.5 g MA, 87.5 g NVP, 12.5 gAA, 15 g SiMac, 397 g MEK, 25 g IPA and 1.1 g Vazo™64 initiator. Theresulting homogeneous mixture was purged with nitrogen at I liter perminute for 5 minutes. The reaction mixture was then sealed in the glassjar and tumbled in a constant temperature bath at 55° C. for 16 hrs. Aviscous milky copolymer solution was obtained having an inherentviscosity of 0.28 dl/g and a solids content of 35.6%. The copolymersolution was then diluted with 428 g of a 50/50 toluene/IPA mixture toachieve a final diluted solids content of 20%.

Comparative Example 1

The procedure of Example 1 was repeated. The charges were as follows:86.3 g MA, 67.1 g NVP, 9.6 g AA, 57.5 g SiMac, 409 g MEK and 1.3 g Vazo™64. A viscous milky copolymer solution was obtained having an inherentviscosity of 0.33 dl/g and a solids content of 34.4%. The copolymersolution was then diluted with 473 g of a 50/50 toluene/IPA mixture toachieve a final diluted solids content of 20%.

Coatings

Coatings comprising the copolymer of the present invention may be usedon a variety of substrates, typically paper. These coatings are uniquein their possession of the following three characteristics, namely,bleedthrough resistance, ink receptivity and receptivity torepositionable pressure sensitive adhesives such as those found onrepositionable notes. The novel coating of the present invention can becoated by any number of coating techniques known to those skilled in theart. An effective coating is one which provides a smooth continuouslayer of copolymer on the substrate and exhibits bleedthroughresistance, ink receptivity and receptivity to repositionable pressuresensitive adhesives such as those found on repositionable PSA notes.

In order to evaluate bleedthrough resistance, ink receptivity andreceptivity to pressure sensitive adhesives such as those found onrepositionable notes, a coating was prepared as follows. Coatings wereprepared of the copolymer solutions from Example 1 on a 15.4 pound (7kg) bond paper roll stock available from Georgia Pacific Inc. The paperrolls were 12 inches in width. The copolymer solution of Example 1 wasdiluted to 12.5% solids and die coated onto one side of the paper baseusing a 12 inch (305 mm) wide modified rotogravure coater. The coatingspeed was set at 25 feet per minute (7.62 meters per minute).

The coated paper was then oven dried at 93° C. The final dried coatingweight was 6.45 g/m². The coated paper substrate was then cut intosingle sheets for testing of bleedthrough resistance, ink receptivity,and receptivity to pressure sensitive adhesives such as those found onrepositionable notes.

In a similar manner a comparative coating was prepared using thecopolymer solution of Comparative Example 1. The coating weight of thiscomparative coating was 6.45 g/m².

Bleedthrough Resistance Test

The coating of the present invention is capable of providing effectivebleedthrough resistance when written on with both solvent-based andwater-based inks. The following test method was used to determinewhether a coating had the property of bleedthrough resistance.

The coating of the present invention (Example 1) and that of ComparativeExample 1 were tested for bleedthrough resistance. The resistance tobleedthrough of a solvent-based (Sanford™ Magnum™ 44 permanent blackmarker available from Sanford Corp., Bellwood, Ill. 60104) and awater-based (Sanford™ Mr. Sketch™ scented instant water color purplemarker available from Sanford Corp., Bellwood, Ill. 60104) marker weretested on paper sheets coated with the coatings of the respectiveexamples. The coated sheet was placed coated side up on top of anothercoated sheet. Each marker was then used to draw one horizontal line onthe coated side of the top sample at moderate speed and very lightpressure. A second horizontal line was then drawn on the coated side ofthe top sample at moderate speed applying a moderate amount of pressure.Finally, a third horizontal line was drawn on the coated side of the topsample at a slow speed while applying the maximum amount of pressure.Bleedthrough of the marker from the top sheet onto the bottom sheet wasthen evaluated and recorded as either none, slight, moderate or heavyfor each coating and each marking pressure (light, medium and heavy).The results of these observations are shown in the Table 1 below.Coatings having effective bleedthrough resistance are defined herein asthose coatings having a bleedthrough score of none.

The results in Table 1 indicate that coatings of the invention as wellas Comparative Example 1 have excellent bleedthrough resistance.

In order to conduct this test, different solvent-based and/orwater-based markers may be used in place of those listed above if theyare unavailable.

                  TABLE 1                                                         ______________________________________                                        Bleedthrough Test                                                                         Light       Moderate Heavy                                        Example*    Pressure    Pressure Pressure                                     ______________________________________                                        Ex. 1 (s)   none        none     none                                         Ex. 1 (w)   none        none     none                                         Comp. Ex. 1(s)                                                                            none        none     none                                         Comp. Ex. 1(w)                                                                            none        none     none                                         ______________________________________                                         *Designation of (s) = solventbased marker, (w) = waterbased marker.      

A coating formed from the copolymer of the invention is capable of beingwritten on effectively with both solvent-based and water-based inks.

Writing Tests (Ink Receptivity)

The following test method was used to determine whether a coating couldbe effectively written on with both solvent-based and water-based inks.

The coating of the present invention (Example 1) and that of ComparativeExample 1 were tested for their ability to be legibly written on by avariety of markers, both solvent and water-based. The markers selectedfor this test included:

A) Marks-A-Lot™ permanent orange marker (Avery Dennison, DennisonDivision of Farmington, Mass.)

B) Sanford™ Expo™ dry erase black marker (Sanford Corporation, Bellwood,Ill.)

C) Sanford™ Sharpie™ fine point black permanent marker

D) Sanford™ Mr. Sketch™ washable blue marker

E) Washable Crayola™ purple marker (Binney & Smith Inc. of Easton, Pa.)

F) Sanford™ Mr. Sketch™ scented instant water color purple marker

G) Sanford™ Flip Chart™ brown marker

The first three markers in this list (A-C) are solvent-based and thelast four (D-G) are water-based.

The name of each marking pen was written with that particular pen on thecoated side of a single paper sheet. The ink was then evaluated visuallyfor spreading, feathering, streaking, beading, fading or any otherundesirable quality. These observations were then recorded as noted inTable 2 as:

Excellent=good writing, no fading, beading or streaking

Very Good=slight beading, fading or streaking (abbreviated as V. Good)

Good=moderate beading, fading or streaking

Fair=heavy beading, fading or streaking

Poor=total beading or fading; unreadable

The coating is considered to be capable of being written on effectivelywith both solvent-based and water-based inks if at least onesolvent-based marker and at least one water-based marker yield a good toexcellent score.

If the above marker(s) are unavailable an alternate water-based and/orsolvent-based marker may be utilized in order to conduct the test.

                                      TABLE 2                                     __________________________________________________________________________    Ink Receptivity                                                                    Marker                                                                             Marker                                                                             Marker                                                                             Marker                                                                             Marker                                                                             Marker                                                                             Marker                                     Example                                                                            A    B    C    D    E    F    G                                          __________________________________________________________________________    Ex. 1                                                                              Excellent                                                                          Excellent                                                                          Excellent                                                                          V. Good                                                                            V. Good                                                                            Excellent                                                                          Excellent                                  Comp.                                                                              Excellent                                                                          Excellent                                                                          Excellent                                                                          V. Good                                                                            Good Excellent                                                                          Excellent                                  Ex. 1                                                                         __________________________________________________________________________

Repositionable Pressure Sensitive Adhesive Note

Adherence Test

A conventional repositionable pressure sensitive adhesive note iscapable of effectively adhering to a coating comprising the copolymer ofthe invention. The following test method was used to determine theeffectiveness of the repositionable pressure sensitive adhesive note inadhering to coatings falling within and outside the scope of theinvention.

The coating of the present invention (Example 1) and that of ComparativeExample 1 were tested for their receptivity to a repositionable pressuresensitive adhesive (PSA) such as that found on repositionable notes suchas Post-it™ Notes and Post-it™ Tape Flags (available from 3M, St. Paul,Minn.). Coated samples were adhered, coated side up, to a 76.2 mm×114.3mm aluminum panel using double sided adhesive tape. A 25.4 mm×76.2 mm (1inch×3 inch) repositionable Post-it™ Note was removed from a note pad(Post-it™ Note Pad #671-3AN available from 3M, St. Paul, Minn.) andadhered to the coated surface by rolling a 2 kg roller one complete trip(back and forth once) across the Post-it™ Note and allowing the weightof the roller itself to adhere the note. Care was taken not to applyadditional pressure to the roller. The Post-it™ Note was then peeled at90 degrees from the coated substrate using a Sintech InsIron (ModelRenew 1122 available from Sintech, Research Triangle Park, N.C.) with acrosshead speed of 305 mm/m and a full scale load of 400 g. The 90degree peel values were recorded in g/25.4 mm width. The results of thispeel test are shown in Table 4 below. "Effective adhesion" was definedas a 90 degree peel value between about 8 and about 95 grams/25.4 mmwidth.

The results in Table 3 indicate significant improvement to thereceptivity to a repositionable pressure sensitive adhesives (PSA) suchas that found on repositionable notes such as Post-it™ Notes (availablefrom 3M, St. Paul, Minn.) on paper substrates coated with the copolymerof the present invention.

                  TABLE 3                                                         ______________________________________                                        Repositionable PSA Adhesion                                                                 Adhesion                                                        Example       (g/25.4 mmm)                                                    ______________________________________                                        Ex. 1         8.5                                                             Comp. Ex. 2   3.3                                                             ______________________________________                                    

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention, and it should be understood that thisinvention is not to be unduly limited to illustrative embodiments setforth herein.

We claim:
 1. A random copolymer comprising the reaction product of:(a) amonomer selected from the group consisting of methyl acrylate, ethylacrylate, and mixtures thereof, (b) a monomer selected from the groupconsisting of N-vinyl pyrrolidone, N-vinyl caprolactam, and mixturesthereof; (c) a monomer selected from the group consisting of acrylicacid, methacrylic acid, itaconic acid, maleic acid, fumaric acid,2-carboxymethyl acrylate, and mixtures thereof; (d) a macromonomerhaving the general formula ##STR4## wherein X is a vinyl grouppolymerizable with the monomers of elements (a), (b) and (c);Y is adivalent linking group selected from the group consisting of --CH₂ --,--CH₂ CH₂ --, and --CH₂ CH₂ CH₂ --; m is 20 to 2000; each R isindependently selected from the group consisting of hydrogen, C₁₋₈alkyl, aryl, and alkoxy; and wherein a coating of the copolymer iscapable of being written on effectively with both solvent-based andwater-based inks; wherein the coating is capable of providing effectivebleedthrough resistance when written on with both solvent-based andwater-based inks; wherein a repositionable pressure sensitive adhesivenote is capable of effectively adhering to the coating.
 2. The randomcopolymer of claim 1 wherein X is selected from the group consisting of:##STR5##
 3. The random copolymer of claim 1 which comprises about 30 toabout 80 weight percent of the monomer of element (a), about 30 to about50 percent of the monomer of element (b), about 3 to about 10 percent byweight of the monomer of element (c), and about 0.5 to about 7 percentby weight of the monomer of element (d), based upon the total weight of(a) plus (b) plus (c) plus (d).
 4. The random copolymer of claim 1 whichcomprises about 50 to about 55 weight percent of the monomer of element(a), about 40 to about 45 percent of the monomer of element (b), about 4to about 7 percent by weight of the monomer of element (c), and about 1to about 3 percent by weight of the monomer of element (d) based uponthe total weight of (a) plus (b) plus (c) plus (d).
 5. The copolymer ofclaim 1 wherein the monomer of element (a) is methyl acrylate, themonomer of element (b) is N-vinyl pyrrolidone, and the monomer ofelement (c) is acrylic acid, and wherein the macromonomer of element (d)is represented by ##STR6## wherein m is 100 to
 150. 6. The copolymer ofclaim 1 having a number average molecular weight of about 20,000 toabout 100,000.
 7. The copolymer of claim 1 having a number averagemolecular weight of about 25,000 to about 50,000.
 8. An articlecomprising a substrate coated with a composition comprising thecopolymer of claim
 1. 9. The article of claim 8 wherein the substrate ispaper.
 10. The copolymer of claim 1 having a glass transitiontemperature ranging from about 40 to about 90 degrees C.
 11. Thecopolymer of claim 1 having a glass transition temperature ranging fromabout 50 to about 80 degrees C.
 12. An article comprising a substratecoated with a coating comprising the copolymer of claim 1;wherein thecoating comprising the copolymer is capable of being written oneffectively with both solvent-based and water-based inks; wherein thecoating comprising the copolymer is capable of providing effectivebleedthrough resistance when written on with both solvent-based andwater-based inks; and wherein a repositionable pressure sensitiveadhesive note is capable of effectively adhering to the coatingcomprising the copolymer.
 13. A pad comprising a plurality of thearticles of claim 12 attached together.
 14. A roll comprising thearticle of claim 12 rolled upon itself.
 15. The article of claim 12wherein the substrate is paper.
 16. The article of claim 12 whichfurther comprises one or more additional coating(s) selected from thegroup consisting of pressure sensitive adhesives and release coatings,wherein said additional coating(s) are coated on the substrate inarea(s) other than where the coating comprising the copolymer is coated.17. A pad comprising:(a) a plurality of paper sheets, each sheet havinga first side and a second side; (b) a layer of pressure sensitiveadhesive adjacent at least an edge of a margin of the first side of eachsheet; (c) a release coating layer positioned on the second side of eachsheet in a position which is opposite that of the pressure sensitiveadhesive layer which is on the first side of the sheet; and (d) acoating layer comprising the copolymer of claim 1 on at least a portionof the second side of each sheet other than where the release coatinglayer is coated; wherein the pad is assembled such that the sheets arestacked one upon another, such that the release coating layer of eachsheet is positioned against the pressure sensitive adhesive layer of asheet which is above it so that an uppermost sheet is removable.
 18. Thepad of claim 17 which further comprises a cardboard backing to which theplurality of sheets are attached.
 19. A roll comprising;(a) a sheet ofpaper having a first side and a second side; (b) a layer of a pressuresensitive adhesive adjacent at least a longitudinal edge of the firstside of the sheet; (c) a layer of a release coating positioned on thesecond side of the sheet, positioned such that it is opposite the layerof pressure sensitive adhesive on the first side of the sheet; (d) acoating comprising the copolymer of claim 1 on at least a portion of thesecond side of the sheet in area(s) where the release coating is notpresent; wherein the sheet of paper is rolled upon itself in such amanner that the release layer is positioned directly against thepressure sensitive adhesive layer.
 20. A roll comprising:(a) a sheet ofpaper having a first side and a second side; (b) a first layer of apressure sensitive adhesive adjacent at least a longitudinal edge of thefirst side of the sheet and a second layer of pressure sensitiveadhesive adjacent at least a portion of another longitudinal edge of thefirst side of the sheet opposite the first layer of pressure sensitiveadhesive; (c) two layers of a release coating on the second side of thesheet, positioned such that one is positioned opposite each layer ofpressure sensitive adhesive on the first side of the sheet; and (d) acoating comprising the copolymer of claim 1 on at least a portion of thesecond side of the sheet in area(s) where the release coating layers arenot present;wherein the sheet of paper is rolled upon itself in such amanner that each release layer is positioned directly against thepressure sensitive adhesive layer which is directly on the opposite sideof the sheet.